Process for synthesizing omega-functionalized acids from fatty acids or fatty esters

Abstract

The subject matter of the invention is a process for synthesizing ω-functionalized acids of formula R—(CH 2 ) n —COOH in which R is COOH or NH 2 CH 2 , from a feedstock of natural origin containing hydroxylated fatty acids.

The invention claimed is: 
     
       1. A process for the synthesis of ω-functionalized acids, wherein said acids are of formula R—(CH 2 ) n —COOH, in which R represents COOH or NH 2 CH 2  and n represents an integer between 9 and 12, they are obtained from a feedstock of natural origin comprising unsaturated hydroxylated fatty acids in the acid, ester or polyol ester form comprising at least 18 carbon atoms per molecule and in that said process comprises the following stages:
 a) hydrogenation of the unsaturated hydroxylated fatty acids, resulting in saturated hydroxylated fatty acids, 
 b) dehydration of the saturated hydroxylated fatty acids, resulting in monounsaturated fatty acids, 
 c) oxidative cleavage at the double bond of the monounsaturated fatty acids, resulting in an α,ω-bifunctional compound from diacid or nitrile-acid. 
 
     
     
       2. The process as claimed in  claim 1 , wherein the hydrogenation stage a) is carried out at a temperature of between 70 and 180° C. under an H 2  pressure of between 1 and 300 bar in the presence of either homogeneous or heterogeneous hydrogenation catalysts. 
     
     
       3. The process as claimed in  claim 2 , wherein said catalysts are noble metals, such as Pt, Pd or Rh, or transition metals, such as Mo, W, Cr, Fe, Co or Ni, used alone or as a mixture, optionally in the form supported on active charcoal, on alumina and on silica. 
     
     
       4. The process as claimed in  claim 2 , wherein said catalysts are chosen from Raney nickel and/or palladium-on-active charcoal. 
     
     
       5. The process as claimed in  claim 1 , wherein the hydrogenation stage a) is carried out under operational conditions such that the effluent resulting from this hydrogenation stage exhibits an iodine number <5 and a hydroxyl number >100 mg KOH/g. 
     
     
       6. The process as claimed in  claim 1 , wherein the stage b) of dehydration of the saturated hydroxylated fatty acids is carried out at a temperature of between 100 and 300° C. and in the presence of an acid catalyst. 
     
     
       7. The process as claimed in  claim 1 , wherein the oxidative cleavage stage c) is carried out using an oxidizing agent selected from the group consisting of KMnO 4 , hydrogen peroxide, and oxidizing ozone, optionally in combination with a catalyst. 
     
     
       8. The process as claimed in  claim 1 , wherein it comprises an additional intermediate stage, between stage b) and stage c), of nitrilation of the acid functional group of the monounsaturated fatty acid, resulting in an unsaturated nitrile. 
     
     
       9. The process as claimed in  claim 1 , wherein it comprises a stage of nitrilation of the acid functional group of the saturated hydroxylated fatty acid resulting from stage a) with concomitant dehydration, resulting in an unsaturated nitrile. 
     
     
       10. The process as claimed in  claim 8 , wherein the nitrilation stage is carried out in the liquid phase or in the gas phase using ammonia at a temperature generally between 150° C. and 350° C. and with a catalyst. 
     
     
       11. The process as claimed in  claim 10 , wherein said nitrilation is carried out in the liquid phase with, as catalyst, a metal oxide which is zinc oxide. 
     
     
       12. The process as claimed in  claim 10 , wherein said nitrilation is carried out in the gas phase with said catalyst being supported on a fixed bed of doped or non-doped alumina. 
     
     
       13. The process as claimed in  claim 8 , wherein the effluent from the nitrilation stage is subjected to the oxidative cleavage stage c), the effluent (comprising the nitrile-acid compound) of which is subjected to a hydrogenation d). 
     
     
       14. The process as claimed in  claim 13 , wherein said hydrogenation is carried out at a temperature of between 70 and 200° C. under an H 2  pressure of between 1 and 300 bar in the presence of either homogeneous or heterogeneous hydrogenation catalysts. 
     
     
       15. The process as claimed in  claim 1 , wherein said ω-functionalized acid is a diacid or an amino acid and in that said feedstock of natural origin comprises unsaturated hydroxylated fatty acids in the ester form (alcohol or polyol ester, such as glycerol ester) with said stages being:
 i) hydrogenation of the hydroxylated ester, 
 ii) dehydration of the hydrogenated hydroxylated ester, 
 iii) hydrolysis of the hydrogenated (and dehydrated) ester in order to obtain the corresponding unsaturated fatty acid and alcohol or polyol, 
 iv) separation of the alcohol or polyol and optionally separation of the unsaturated fatty acid isomers, 
 v) optionally (only in the case of nitrile), ammoniation of the unsaturated (fatty) acid in order to obtain the corresponding unsaturated nitrile, 
 vi) oxidative cleavage of the unsaturated nitrile or fatty acid (as the case may be), 
 vii) optionally, separation of the cleavage products and light acids formed, 
 viii) optionally (case of nitrile), hydrogenation of the nitrile-acid in order to form the corresponding amino acid, and 
 ix) separation and purification of the diacid formed or of the amino acid formed, as the case may be. 
 
     
     
       16. The process as claimed in  claim 1 , wherein said ω-functionalized acid is an amino acid and in that said feedstock of natural origin comprises unsaturated hydroxylated fatty acids in the ester form and said process comprises the sequence of the following stages:
 i) hydrogenation of the hydroxylated ester, 
 ii) hydrolysis of the hydrogenated ester in order to obtain the corresponding saturated fatty acid and alcohol or polyol, 
 iii) separation of the alcohol or polyol with optional separation of the saturated fatty acids from the hydroxylated fatty acids, 
 iv) ammoniation of the saturated hydroxylated acid, with simultaneous dehydration, in order to obtain the corresponding unsaturated nitrile, 
 v) optionally, separation of the unsaturated nitrile isomers, 
 vi) oxidative cleavage of the unsaturated nitrile, 
 vii) optionally, separation of the nitrile-acid cleavage products and of the light acids formed, 
 viii) hydrogenation of the nitrile-acid, in order to obtain the corresponding amino acid, and 
 ix) separation and purification of the amino acid obtained. 
 
     
     
       17. The process as claimed in  claim 1 , wherein said ω-functionalized acid is an amino acid via a nitrile-acid, starting from a vegetable oil source which has a low concentration of hydroxylated acid, with a sequence of following stages:
 i) alcoholysis of the vegetable oil, optionally concomitant with its extraction from the seed, 
 ii) extraction of a fraction rich in hydroxylated acid ester, 
 iii) hydrogenation of the hydroxylated ester, 
 iv) optionally, hydrolysis of the hydrogenated ester in order to obtain the corresponding fatty acid, 
 v) ammoniation of the saturated hydroxylated acid with simultaneous dehydration (including on ester of stage iii) or on acid of stage iv)), in order to obtain the unsaturated nitrile, 
 vi) optionally, separation of the unsaturated nitrile isomers, 
 vii) oxidative cleavage of the unsaturated nitrile, 
 viii) optionally, separation of the nitrile-acid cleavage products and of the light acids formed, 
 ix) hydrogenation of the nitrile-acid in order to obtain the amino acid, and 
 x) separation and purification of the amino acid obtained. 
 
     
     
       18. A process for the synthesis of an unsaturated fatty nitrile from a charge of natural origin containing unsaturated hydroxylated fatty acids in the acid ester or polyol ester form and bearing at least 18 carbon atoms per molecule, wherein said process comprises the following steps:
 a) hydrogenation of the unsaturated hydroxylated fatty acids leading to saturated hydroxylated fatty acids, 
 b) dehydration of the saturated hydroxylated fatty acids leading to monounsaturated fatty acids, and 
 c) nitrilation after step b) of the acid function of said mono unsaturated acid, thus leading to an unsaturated fatty nitrile. 
 
     
     
       19. The process in  claim 18 , which further comprises a nitrilation step of the acid function of said saturated hydroxylated fatty acid issued from step a), with simultaneous dehydration step b) of said acid and this leading to said unsaturated fatty nitrile. 
     
     
       20. The process of  claim 18 , wherein the said nitrilation step occurs in liquid phase or in gas phase using ammonia at a temperature between 150° C. and 350° C., with a catalyst. 
     
     
       21. The process of  claim 20 , wherein the said nitrilation occurs in liquid phase with a catalyst as a metallic oxide which is zinc oxide. 
     
     
       22. The process of  claim 20 , wherein the nitrilation step occurs in gas phase with said catalyst being supported by an alumina fixed bed, which may be doped or not doped. 
     
     
       23. A process of synthesis of an unsaturated fatty nitrile from a natural origin charge, comprising unsaturated hydroxylated fatty acids in the form of an ester which is an oil of hydroxylated fatty acid, the process comprising the steps of:
 i) hydrogenation of said oil, 
 ii) dehydration of the hydrogenated hydroxylated oil of step i), 
 iii) hydrolysis of the hydrogenated and dehydrated oil of step ii) for obtaining the corresponding unsaturated acid and glycerol, 
 iv) separation of the glycerol, and 
 v) ammoniation of the unsaturated fatty acid for obtaining the corresponding unsaturated fatty nitrile. 
 
     
     
       24. The process of  claim 23 , wherein the hydrolysis step occurs after step i) and dehydration occurs simultaneously with ammoniation of the saturated hydroxylated fatty acid, for obtaining said unsaturated nitrile. 
     
     
       25. An unsaturated fatty nitrile, wherein it is obtained by a process as defined in  claim 18 . 
     
     
       26. The process of  claim 6 , wherein the acid catalyst is selected from the group consisting of sulfuric acid, phosphoric acid, sulfonic acids, alkyl sulfonates, and ion-exchange acid resins. 
     
     
       27. The process of  claim 7 , wherein the oxidative cleavage stage c) is carried out by using ozone in combination with oxygen. 
     
     
       28. The process of  claim 7 , wherein the catalyst comprises tungstic acid.